I coincidentally read two books in a row where the British prime minister is a dark magician:
The setting is the French and Haitian Revolutions and the abolitionist movement in Britain, but where magic is real (and reserved for aristocrats). Seems like a fun concept, but the book itself was generally drier than I expected. True to the spirit of history, if not the letter of real history – things don’t really conclude satisfactorily, good intentions often lead to abuses, no ethical system is completely internally consistent, etc.
This begins a new series after the end of the Laundry Files and the failure of its mission. The world is now ruled by tyrannical and mercurial elder gods, and magic and strange superpowers are on the rise. The original series was a wild mix of Lovecraftian horror, spy thriller, science fiction, and bureaucratic humor; the new cast of characters is a bit more punk and it wouldn’t surprise me if there’s a full-on rebellion as the series progresses.